Automatic telephone system



E. JACOBSEN.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION men MAR. 25. I9I8.

1,349,138 1 Patented Aug. 10, 1920.

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Invent]? Elm! Jacubsen 6- 74%. v filzurney E. JACOBSEN. AUTOMATIC TELEPHONE SYSTEM.

APPLICAHON HLEDMAR.25,19I8. 1,349,381 Patented Aug. 10, 1920.

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JE'EUEUZ'UP Erml JisUtEEn HZZUTE'ZE connector has certain UNITED STATES PATENT OFFICE.

COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINDIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed March 25, 1918.

To (12 Z "whom it may concern Be it known. that I, EMIL JACOBSEN,- a citizen of the United States of America, and a resident of Chicago, Cook county, and State of Illinois, have invented. certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates in general to an automatic telephone system in which connections are controlled solely by the subscribers, and more specifically to that type of an automatic system in which a number of selector switches and a connector switch are used in the establishment of a connection and in which the release of the connector switch is controlled by the last party to hang up his receiver. That is when the calling sub scriber hangs up first the connection is re leased but the last switch or connector switch is held on the called line by the called subscriber who then releases it when he hangs up his receiver.

An. object of my invention is to soarrange the circuits of said connector that when a calling subscriber has released a connection and the connector is being held by a called subscriber, another calling subscriber may seize this connector switch, release it from the called line and use it for establishing another connection. Further details and objects and the method of operation will be pointed out in the following; specification.

In the drawings, I have shown an established connection between a calling subscriber A (Figure 1) and a called subscriber B, (Fig. 2) which connection is established through the medium of a line switch C, selector E and a connector switch H, which other improvements which will be pointed out.

The substations A and B are of the usual common battery type comprising the usual transmitter 2, receiver 3, call signal 5 and a calling device CD of well known type for interrupting the line circuit to send impulses.

The line switch C is of a well known rotary type comprising a line relay 6, switching relay 7 and rotary magnet 8. The selector E of the well known Keith-Ericks0n two wire type in which the side switch has been omitted and the relays are controlled over the two sides of a calling line in series.

The connector switch H (Fig. 2) is also Specification of Letters Patent.

' the last one to Patented Aug. 10, 1920. Serial No. 224,429.

of the Keith-Erickson type in which the relays are controlled over two sides of a calling line in series to establish a connection and in which the release is controlled by either the calling or the called man, that is, hang up. I will describe the operation in detail when the subscriber A calls subscriber B by referring to the draw- IHOS.

When the receiver at substation A is removed, the closure of springs 4: by the receiver hook closes a circuit for line relay 6, which in turn closes a. circuit for relay 7 and magnet 8 in series. Relay 7 is however short circuited by ground from the private wiper 10 and by said ground to find an idle trunk, at which time relay 7 is no longer short circu ted and energizes to extend the line cir cult to selector E through thesprings 12 and 13 thereby closing a circuit for the line relay 14 of selector E. The line relay 14:, upon energizing, closes a circuit for slow release relay 17 in the usual manner to connect ground to the release trunk to maintain the relay 7 of switch C energized and to make the trunk line busy at contact 70. The first series of impulses from the subscriber A operates the line relay 14 in the usual manner to operate the vertical magnet 71, thereby raising the wipers 72, 73 and 74; to a desired level of the bank. The off normal springs 75 and 76 close to prepare certain circuits as soon as the switch leaves normal. The slow relay 77 energizes during the operation of magnet 71 and closes a circuit for relay 78 at springs 79 and 80. Relay 78 energizes to prepare the circuit of magnet 81 at springs 82 and locks itself through springs 84, springs 83, springs 89, springs 76 and through its own winding to battery. As soon as relay 77 denergizes after the vertical impulses, the circuit for magnet 81 is completed at springs 79 and 85. Magnet 81 operates to step the wipers one step and opens the circuit of relay 78 at springs 89, relay 78 therefore deenergizes and opens the circuit of magnet 81. If the connected trunk is busy, ground from wiper 74 will again energize relay 78 through springs 86 and 87 and springs 89 and 76, so that the rotary magnet will again operate. This operation of relay 78 and magnet 8L continues until an idle trunk is found, at which time relay 88 which has hcretoihrc magnet 8 is operatedbeen short circuited, operates in series with magnet 78 to disconnect the relays of the switch E from the line circuit and extend the line circuit to the selected trunk, from which a ground is fed. back a short time later over the private wiper 7st to hold the relay 88 energized. Relay '78 does not operate at this time due to the high resistance of relay 88. The energization ot relay 88 at this time closes a circuit for the line relay 15 of connector H, which relay immediately energizes over the line circuit and closes a circuit for the slow release relay 16. Relay 16 energizes to provide a holding circuit for relay of line switch C through springs 18, opens the circuit of the release magnet 19 at one point and prepares a circuit for the vertical magnet 20 and slow relay 21. The subscriber now operates the springs CD to interrupt the circuit of relay 15 a number of times. Each time relay 15 deenergizes, a circuit is closed from ground through springs 22 and 23, springs 24:, springs 25 and 26, and magnet 20 and relay 21 to battery. Magnet 20 therefore operates to raise the wipers 27, 28 29 and 30 to some level-of the connector a 0 a n 0 banks. The initial circuit for energizing the vertical magnet is opened at springs 25 and 26 as soon as the switch leaves normal position but a new circuit is closed through springs 25 and 31, springs 32 and 33 and through magnet 20 and relay 21 to battery. As soon as the first series of impulses. cease, relay 21 deenergizes to open the circuit of magnet 20 and close point in the circuit of rotary magnet 34. When the line relay 15 operates in response to the next series of impulses it operates the magnet 34 over a circuit from ground through springs 22 and 23, springs 24:, springs 25 and 31, springs 32 and 35, slow relay 36, springs 87, springs 38 and 39, and magnet 34 to battery. lilagnet 3a therefore operates to rotate the wipers 273(l inclusive to a set of contacts to which the desired line is connected. The relay 36 remains energized, during the operation of magnet 3e and "for a short interval alter the impulses to said magnet cease, so that the test wiper 29 is held in connection with the relay 4:0 for an instant. l1"- the called line is busy. at ground will be present at said wiper and relay 4-0 will energize to prepare locking circuit for itself which is closed when relay 36 deenergizes and extends from ground through springs ll and d2 of relay l6, springs as and 4A, springs 45 and 46, springs 47. and relay 4-0 to battery. llelay 40 also disconnects the rotary magnet springs 37 and connects the busy signal to the calling subscriben who may then release the connection in the usual manner by restoring his receiver. Relays 15 and 16 will then deenergize and close a circuit for the release magnet from ground through springs l1 and ll-8, springs 19 and 50, anl magnet 19 to battery.

Assuming the called line to be idle when connection is extended thereto then relay 4-0 will not be energized and when relay 36 falls back a circuit will be closed for the lower winding of relay 51 extending from ground through springs ll and L2, springs a3 and ll, springs 4:5 and 52, winding of said relay, springs 53, springs 54. and 55, wiper 29, and cut-off winding of switch C to bat tery. Relay 51 therefore energizes and locks itself to ground tl'irough springs 56. The relay 51 also opens the circuit for its lower winding and connects ground direct to the Wiper 29 through springs 57 and 55, while the springs 58 close the talking circuit at one point. The springs 49 open another point in the circuit of release magnet 19. The closure of springs 58 connects interrupted generator to the called line in series with ring cut-oil relay 59 which is energized when the called subscriber answers to cut oil the ringing current, locks itself energized, and cuts the talking; circuit through at springs 60 and 61 and connects ground to the upper one of the springs l9 through springs 62. As soon as the talking circuit is cut through by springs 60 and 61, the back bridge relay 63 is energized in series with the called line to reverse battery to the walling line for any desired purpose. Conversation may now proceed over the heavy conductors shown. When conversation is completed, the connection is released in the tollowing manner: Should the calling subscriber restore his receiver first, the line relay 15 will deenerg'ize and open the circuit of slow release relay 16. Relay 16 will also deenergize to remove ground from the holdingr circuit of line switch C at springs 18, opens the springs 41 and s2, and closes springs ll and 8. The springs s1 and 42 do not open until springs 22 and 2?) come into contact so that ground through springs 22 and and springs 64 replaces the ground through springs 41 and 42 in the holding circuit of relay 51 which therefore remains energized to hold the circuit of the release magnet 19 open at springs l9. hen the called subscriber hangs up, relay 33 dciinerand opens the circuit ot relay 5i at springs 64. Relay 51 will thereiore del nergize. close the circuit of the release mag:- net at springs s9, and open the holding circuit of ring cut-off relay 5%) at spring 39. The connector ll will be released therefore and restored to normal position. it will be noted that while the switch H is being held by the called subscriber and alter the calling); subscriber has restored his receiver that the switch H is accessible to another calling: subscriber. That is, when relays l5 and 16 deenergiae, the guarding ground for the said connector from springs 18 to the test contact is removed. N ow should another subscriber similar to A. seize the connector H to extend another call. means is provided for releasing said switch II- I'IOlll the called subscribers line. This result is accomplished as follows: When such a connection is established, a circuit is closed for line relay 15 in series with this second line in the same manner as when subscriber A called. Relay 15, upon energizing, opens the springs and 23 to open the holding circuit of ].Bl1 5.1. Relay 51 deenergizes and a circuit is then closed for release magnet 19 extending from ground through springs 62, springs 4:9, springs 50 and said magnet to battery. The switch H is therefore released regardless of the fact that a called subscriberis holding the same and may be used by the second calling man to call another party. This connector switch is also provided with means for automatically selecting any one of a group of contacts in an improved manner. Certain levels of the bank in this switch may be divided up into groups, that is, the switch may he stepped to a certain level and may then rotate automatically over a number of trunks to pick out an idle one. At 90, 91 and 92 are shown a part of anotherlevel showing one group of the private contacts ot such level. In this case all but the last of such pairs of private contacts will be strapped together as at 90 and 91 while the last pair are left open. Now if the last switch is directed to the contact- 90 and it said contact is idle, the switch will cut through in the same manner as explained; but, if such contact be busy and a ground is connected to the lower contact then this ground will pass through wiper 28, through springs 94:, springs 95, springs 96. and through relays 93 and 21 to battery. Relay 93 will therefore energize to close a circuit for rotary magnet 34 at springs 96 to rotate the wipers onto the next set of contacts 91. Rotary magnet 34, upon energizing, opens the circuit of relay 93 at springs 96' so that relay will again deenergize and the operation may proceed with regard to contacts 91, where the same operation will occur. It the first two pairs of contacts are busy and the switch rotates to contacts 9:2 then the switch will stop and test in the same manner as when calling substation B and it this is also busy then a busy signal will be given from relay 40 in the usual manner.

It will be seen therefore that I have pro vided an improved and ethcient manner of holding a connector switch selectable and releasable while being held by a previously called party and that said switch also operates in an improved manner to select one of a group of trunks automatically.

What I claim as my invention is:

1. In a telephone system, calling and called lines, a plurality of automatic switches for establishing a connection between a calling and a called line, means controlled by the calling subscriber for releasing the connection, means controlled by the called subscriber for preventing the release of the last of said switches in the connection when the connection is released, means for making said switch busy to other calls while the connection is established and means for removing said busy condition while the switch is being held by the called subscriber wherebysaid switch may be automatically released by another-subscriber and used for another call.

2. In a telephone system, calling and called lines, a plurality of automatic switches for establishing a connection be tween a calling and a called line, means controlled by the calling subscriber for releasing the connection, means controlled by the called subscriber for preventing the release of the last of said switches in the connection when the connection is released, means for making said switch busy to other calls while the connection is established, means for removing said busy condition while the switch is being held by the called subscriber whereby said switch may be used for another call, and means controlled by the establishment of a second connection" to said last switch for releasing the same from the called line.

3. In a telephone system, a connector switch, a plurality of selector switches, means for operating one of said selector switches to seize said connector to extend a connection to a called line, means for making said connector busy to calls from any other of said selector switches w iile the connection is established, means for releasing the connection, means controlled by the called subscriber for holding the connection from the connector to the called line, and means for removing said busy conditionwhile the connection is being held by the called subscriber to permit another selector to seize and automatically release the same.

4:. In a telephone system, a connector switch, a plurality of selector switches, means for operating one of said selector switches to seize said connector to extend a connection to a called line, means for making said connector busy to calls from another of said selector switches while the connection is established, means for releasing the connection, means controlled by the called subscribed for holding the connection from the connector to the called line, means for removing said busy condition while the connection. is being held by the called subscriber to permit another selector to seize the same, and means for releasing said connector switch from the called line when seized by another selector while being held by the called subscriber.

5. In a telephone system, calling and called lines, a plurality of automatic switches, means controlled by the calling subscriber for seizing said switches successively to extend a connection to the called subscriber and for making each switch busy to other calls while seized, means controlled by the calling subscriber for releasing said switches, means controlled by the called subscriber for preventing the release of one of said switches and for making said one switch accessible to further calls, and means for removing said last mentioned switch from further control by the called subscriber when seized by another calling subscribe-r,

6. In a telephone system, calling and called lines, a plurality of automatic switches, means controlled by the calling subscriber for seizing said switches successively to extend a connection to the called subscriber and, for making each switch busy to other calls while seized, means controlled. by the calling subscriber for releasing said switches, means controlled by the called subscriber for preventing the release of one of said switches and for making said one switch accessible to further calls, means for seizing said one switch while held by the called subscriber, and means controlled by the seizure of said switch for automatically releasing said switch.

Signed by me at Chicago, Illinois, this 21st day of March, 1918.

EMIL JACOBSEN. 

